Research and development of the organic TFT using organic semiconductor materials elements are progressed earnestly as technologies to complement do disadvantage of thin-film transistor (referred as TFT hereafter) element using conventional silicon material, recently (refer to Patent document 1, Non-patent document 1 and so on).
The organic TFT elements can be manufactured in a process at low temperature, and is available to use resin supports which is light and difficult to break, and further, a flexible display using resin film as a support can be realized (refer to non-patent document 2). A display of excellent productivity with low cost can be realized by using an organic semiconductor material which can be manufacturer by a wet process such as printing and coating at atmospheric pressure.
However, a layer of the organic semiconductor material is formed by vapor deposition such as employing a vacuum deposition method, since low molecular weight type organic semiconductor material having relatively high mobility is hard to be dissolved in a solvent. Further control of equipment or process is difficult since the manufacture is performed in by the vacuum condition a vacuum deposition method.
On the other hand, polymer type an organic semiconductor material excellent in solubility and suitable for a solution printing process such as an ink jet method and a spin coat method is low mobility and has a problem in reliability for long time.
An organic TFT is reported, in which organic TFT semiconductor layer is formed by forming a precursor film of soluble pentacene, which is a low molecular weight high mobility organic semiconductor material by a coating method, then it is converted to pentacene by heat treatment to improving the problems (refer to non-patent document 3).
Further, an organic TFT is reported in which semiconductor layer is formed by forming a soluble precursor of tetrabenzoporphyrin type compound semiconductor material by a coating method, then is converted crystalline porphyrin type compound semiconductor (refer to patent document 2).    Patent document 1: JP-A H10-190001    Patent document 2: JP-A 2003-304014    Non-patent document 1: Advanced Material, 2002, No. 2, page 99 (Review)    Non-patent document 2: SID' 01 Digest, page 57.    Non-patent document 3: Journal of American Chemical Society, 2002, No. 124, page 8812.